staging: wilc1000: use RCU list to maintain vif interfaces list

Make use of RCU list to maintain virtual interfaces instead of an array.
The update operation on 'vif' list is less compare to the read
operations. Mostly the 'vif' list elements are accessed for the read
operation, so RCU list is more suited for this requirement.
The shifting of interface index id's during the delete interface is not
required. As the firmware only supports 2 interfaces so make use of
available free slot index id during add interface.

Signed-off-by: Ajay Singh <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: ajaykathat

drivers/staging/wilc1000/wilc_hif.c

@@ -183,11 +183,17 @@ int wilc_get_vif_idx(struct wilc_vif *vif)
 static struct wilc_vif *wilc_get_vif_from_idx(struct wilc *wilc, int idx)
 {
 	int index = idx - 1;
+	struct wilc_vif *vif;
 
 	if (index < 0 || index >= WILC_NUM_CONCURRENT_IFC)
 		return NULL;
 
-	return wilc->vif[index];
+	list_for_each_entry_rcu(vif, &wilc->vif_list, list) {
+		if (vif->idx == index)
+			return vif;
+	}
+
+	return NULL;
 }
 
 static int handle_scan_done(struct wilc_vif *vif, enum scan_event evt)

drivers/staging/wilc1000/wilc_netdev.c

@@ -97,29 +97,25 @@ void wilc_mac_indicate(struct wilc *wilc)
 static struct net_device *get_if_handler(struct wilc *wilc, u8 *mac_header)
 {
 	u8 *bssid, *bssid1;
-	int i = 0;
 	struct net_device *ndev = NULL;
+	struct wilc_vif *vif;
 
 	bssid = mac_header + 10;
 	bssid1 = mac_header + 4;
 
-	mutex_lock(&wilc->vif_mutex);
-	for (i = 0; i < wilc->vif_num; i++) {
-		if (wilc->vif[i]->mode == WILC_STATION_MODE)
-			if (ether_addr_equal_unaligned(bssid,
-						       wilc->vif[i]->bssid)) {
-				ndev = wilc->vif[i]->ndev;
+	list_for_each_entry_rcu(vif, &wilc->vif_list, list) {
+		if (vif->mode == WILC_STATION_MODE)
+			if (ether_addr_equal_unaligned(bssid, vif->bssid)) {
+				ndev = vif->ndev;
 				goto out;
 			}
-		if (wilc->vif[i]->mode == WILC_AP_MODE)
-			if (ether_addr_equal_unaligned(bssid1,
-						       wilc->vif[i]->bssid)) {
-				ndev = wilc->vif[i]->ndev;
+		if (vif->mode == WILC_AP_MODE)
+			if (ether_addr_equal_unaligned(bssid1, vif->bssid)) {
+				ndev = vif->ndev;
 				goto out;
 			}
 	}
 out:
-	mutex_unlock(&wilc->vif_mutex);
 	return ndev;
 }
 
@@ -137,13 +133,16 @@ void wilc_wlan_set_bssid(struct net_device *wilc_netdev, u8 *bssid, u8 mode)
 
 int wilc_wlan_get_num_conn_ifcs(struct wilc *wilc)
 {
-	u8 i = 0;
+	int srcu_idx;
 	u8 ret_val = 0;
+	struct wilc_vif *vif;
 
-	for (i = 0; i < wilc->vif_num; i++)
-		if (!is_zero_ether_addr(wilc->vif[i]->bssid))
+	srcu_idx = srcu_read_lock(&wilc->srcu);
+	list_for_each_entry_rcu(vif, &wilc->vif_list, list) {
+		if (!is_zero_ether_addr(vif->bssid))
 			ret_val++;
-
+	}
+	srcu_read_unlock(&wilc->srcu, srcu_idx);
 	return ret_val;
 }
 
@@ -167,16 +166,16 @@ static int wilc_txq_task(void *vp)
 		do {
 			ret = wilc_wlan_handle_txq(wl, &txq_count);
 			if (txq_count < FLOW_CONTROL_LOWER_THRESHOLD) {
-				int i;
+				int srcu_idx;
 				struct wilc_vif *ifc;
 
-				mutex_lock(&wl->vif_mutex);
-				for (i = 0; i < wl->vif_num; i++) {
-					ifc = wl->vif[i];
+				srcu_idx = srcu_read_lock(&wl->srcu);
+				list_for_each_entry_rcu(ifc, &wl->vif_list,
+							list) {
 					if (ifc->mac_opened && ifc->ndev)
 						netif_wake_queue(ifc->ndev);
 				}
-				mutex_unlock(&wl->vif_mutex);
+				srcu_read_unlock(&wl->srcu, srcu_idx);
 			}
 		} while (ret == -ENOBUFS && !wl->close);
 	}
@@ -725,14 +724,15 @@ netdev_tx_t wilc_mac_xmit(struct sk_buff *skb, struct net_device *ndev)
 						wilc_tx_complete);
 
 	if (queue_count > FLOW_CONTROL_UPPER_THRESHOLD) {
-		int i;
+		int srcu_idx;
+		struct wilc_vif *vif;
 
-		mutex_lock(&wilc->vif_mutex);
-		for (i = 0; i < wilc->vif_num; i++) {
-			if (wilc->vif[i]->mac_opened)
-				netif_stop_queue(wilc->vif[i]->ndev);
+		srcu_idx = srcu_read_lock(&wilc->srcu);
+		list_for_each_entry_rcu(vif, &wilc->vif_list, list) {
+			if (vif->mac_opened)
+				netif_stop_queue(vif->ndev);
 		}
-		mutex_unlock(&wilc->vif_mutex);
+		srcu_read_unlock(&wilc->srcu, srcu_idx);
 	}
 
 	return 0;
@@ -810,14 +810,13 @@ void wilc_frmw_to_host(struct wilc *wilc, u8 *buff, u32 size,
 
 void wilc_wfi_mgmt_rx(struct wilc *wilc, u8 *buff, u32 size)
 {
-	int i = 0;
+	int srcu_idx;
 	struct wilc_vif *vif;
 
-	mutex_lock(&wilc->vif_mutex);
-	for (i = 0; i < wilc->vif_num; i++) {
+	srcu_idx = srcu_read_lock(&wilc->srcu);
+	list_for_each_entry_rcu(vif, &wilc->vif_list, list) {
 		u16 type = le16_to_cpup((__le16 *)buff);
 
-		vif = netdev_priv(wilc->vif[i]->ndev);
 		if ((type == vif->frame_reg[0].type && vif->frame_reg[0].reg) ||
 		    (type == vif->frame_reg[1].type && vif->frame_reg[1].reg)) {
 			wilc_wfi_p2p_rx(vif, buff, size);
@@ -829,7 +828,7 @@ void wilc_wfi_mgmt_rx(struct wilc *wilc, u8 *buff, u32 size)
 			break;
 		}
 	}
-	mutex_unlock(&wilc->vif_mutex);
+	srcu_read_unlock(&wilc->srcu, srcu_idx);
 }
 
 static const struct net_device_ops wilc_netdev_ops = {
@@ -843,7 +842,8 @@ static const struct net_device_ops wilc_netdev_ops = {
 
 void wilc_netdev_cleanup(struct wilc *wilc)
 {
-	int i;
+	struct wilc_vif *vif;
+	int srcu_idx;
 
 	if (!wilc)
 		return;
@@ -853,14 +853,32 @@ void wilc_netdev_cleanup(struct wilc *wilc)
 		wilc->firmware = NULL;
 	}
 
-	for (i = 0; i < wilc->vif_num; i++) {
-		if (wilc->vif[i] && wilc->vif[i]->ndev)
-			unregister_netdev(wilc->vif[i]->ndev);
+	srcu_idx = srcu_read_lock(&wilc->srcu);
+	list_for_each_entry_rcu(vif, &wilc->vif_list, list) {
+		if (vif->ndev)
+			unregister_netdev(vif->ndev);
 	}
+	srcu_read_unlock(&wilc->srcu, srcu_idx);
 
 	wilc_wfi_deinit_mon_interface(wilc, false);
 	flush_workqueue(wilc->hif_workqueue);
 	destroy_workqueue(wilc->hif_workqueue);
+
+	do {
+		mutex_lock(&wilc->vif_mutex);
+		if (wilc->vif_num <= 0) {
+			mutex_unlock(&wilc->vif_mutex);
+			break;
+		}
+		vif = wilc_get_wl_to_vif(wilc);
+		if (!IS_ERR(vif))
+			list_del_rcu(&vif->list);
+
+		wilc->vif_num--;
+		mutex_unlock(&wilc->vif_mutex);
+		synchronize_srcu(&wilc->srcu);
+	} while (1);
+
 	wilc_wlan_cfg_deinit(wilc);
 	wlan_deinit_locks(wilc);
 	kfree(wilc->bus_data);
@@ -869,6 +887,23 @@ void wilc_netdev_cleanup(struct wilc *wilc)
 }
 EXPORT_SYMBOL_GPL(wilc_netdev_cleanup);
 
+static u8 wilc_get_available_idx(struct wilc *wl)
+{
+	int idx = 0;
+	struct wilc_vif *vif;
+	int srcu_idx;
+
+	srcu_idx = srcu_read_lock(&wl->srcu);
+	list_for_each_entry_rcu(vif, &wl->vif_list, list) {
+		if (vif->idx == 0)
+			idx = 1;
+		else
+			idx = 0;
+	}
+	srcu_read_unlock(&wl->srcu, srcu_idx);
+	return idx;
+}
+
 struct wilc_vif *wilc_netdev_ifc_init(struct wilc *wl, const char *name,
 				      int vif_type, enum nl80211_iftype type,
 				      bool rtnl_locked)
@@ -909,10 +944,14 @@ struct wilc_vif *wilc_netdev_ifc_init(struct wilc *wl, const char *name,
 
 	ndev->needs_free_netdev = true;
 	vif->iftype = vif_type;
-	vif->wilc->vif[wl->vif_num] = vif;
-	vif->idx = wl->vif_num;
-	wl->vif_num += 1;
+	vif->idx = wilc_get_available_idx(wl);
 	vif->mac_opened = 0;
+	mutex_lock(&wl->vif_mutex);
+	list_add_tail_rcu(&vif->list, &wl->vif_list);
+	wl->vif_num += 1;
+	mutex_unlock(&wl->vif_mutex);
+	synchronize_srcu(&wl->srcu);
+
 	return vif;
 }